Submitted to: ASA-CSSA-SSSA Annual Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: November 6, 2003
Publication Date: November 6, 2003
Citation: KASPAR, T.C., PARKIN, T.B., JAYNES, D.B. CHANGES IN SOIL CARBON RESPONSE TO YEAR, PREVIOUS CROP, AND COVER CROP. ASA-CSSA-SSSA ANNUAL MEETING ABSTRACTS. 2003. CD-ROM. MADISON, WI. Technical Abstract: To evaluate management effects on soil carbon, spatial and temporal variability must be accounted for. Soil samples from the 0-5 cm layer were taken in a 7.62 m grid pattern in two adjacent fields in both phases of a no-till corn-soybean rotation in each of three years and analyzed for carbon using the weight-loss-on-ignition method. Elevations were measured with a kinematic global positioning system and a digital elevation model was used to estimate elevation, slope, plan curvature, and profile curvature of the sampling positions. The large spatial variation of soil carbon at this site seems to be related to landscape position and past erosion. A regression equation including elevation, slope, and plan curvature accounted for 69% of the spatial variation. Spatial effects related to terrain were removed by subtracting predicted values from actual values and examining the residuals. Average soil carbon levels increased 278 g of C/m2 between sampling dates in 2000 and 2001. No effects of previous crop and cover crop management on soil carbon levels could be detected. By accounting for terrain effects and taking a large number of samples, a relatively small change in soil carbon levels was detected between years; but no effects of previous crop or management were detected, emphasizing the difficulty of investigating management effects on soil carbon.